At the heart of the new RP90 is DigiTech's AudioDNA2 DSP engine, offering four times the power as the previous AudioDNA processor. AudioDNA2 is a proprietary audio ASIC used to provide maximum accuracy in the tone and dynamic response of these new RP Series processors. The RP90 adds an expression pedal for control of effects parameters.

Using DigiTech's newly added Tone and Effects Library buttons, it is easy to dial in the perfect sound using a simple three step process, however the RP90 is also infinitely "tweakable" using the RP's intuitive interface. With pre-designed combinations of models that are accessible as fast as the user can hit the button, the RP90 is guaranteed to find sounds that fit a multitude of playing styles including some of the most aggressive sounds on the available.